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Isolation of carbapenem-resistant Pseudomonas spp. from food
Marcus Ho-Yin Wong1, Edward Wai Chi Chan1, Sheng Chen1
1Shenzhen Key Laboratory for Food Biological Safety Control, Food Safety and Technology Research Centre, The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, PR China; State Key Laboratory of Chirosciences, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
Abstract:
Pseudomonas spp. are ubiquitous in nature. Carbapenem resistance in environmental isolates of members of this genus is thought to be rare but the exact resistance rate is unknown. In this study, carbapenem-resistant Pseudomonas spp. were isolated from chicken and pork samples and the mechanisms underlying the carbapenem resistance in these strains were investigated. A total of 16 carbapenem-resistant Pseudomonas aeruginosa, Pseudomonas putida and Pseudomonas otitidis isolates were recovered from eight samples of chicken and pork. The isolates exhibited meropenem minimum inhibitory concentrations (MICs) of 8 to ≥32mg/L and imipenem MICs of <0.5-16mg/L yet did not harbour any acquired carbapenemase genes. Meropenem resistance in various strains was found to be mediated by efflux systems only, whereas overexpression of MexAB-OprM efflux pump and lack of OprD porin were responsible for carbapenem resistance in P. aeruginosa. The intrinsic metallo-β-lactamase gene blaPOM in P. otitidis and overexpression of the TtgABC efflux system in P. putida were also responsible for carbapenem resistance in these organisms. In conclusion, this study reports for the first time the isolation of carbapenem-resistant P. aeruginosa, P. otitidis and P. putida strains from food. The resistance mechanisms of these strains are rarely due to production of carbapenemases. Further selection of such carbapenem-resistant Pseudomonas spp. in the environment and the risk by which they are transmitted to clinical settings are of great public health concern.
Insights
Carbapenem-resistant Pseudomonas bacteria were found in chicken and pork. Resistance mechanisms involved efflux pumps and porin loss, not carbapenemase genes, raising public health concerns.
Area of Science:
- Microbiology
- Antimicrobial Resistance
- Food Safety
Background:
- Pseudomonas species are widespread environmental bacteria.
- Carbapenem resistance in environmental Pseudomonas is not well-quantified.
- Food sources may harbor carbapenem-resistant Pseudomonas.
Purpose of the Study:
- To isolate and characterize carbapenem-resistant Pseudomonas from food samples.
- To investigate the genetic mechanisms of carbapenem resistance in these isolates.
Main Methods:
- Isolation of carbapenem-resistant Pseudomonas from chicken and pork samples.
- Determination of meropenem and imipenem minimum inhibitory concentrations (MICs).
- Analysis of carbapenemase genes and investigation of resistance mechanisms (efflux pumps, porins).
Main Results:
- 16 carbapenem-resistant Pseudomonas aeruginosa, Pseudomonas putida, and Pseudomonas otitidis isolates were recovered.
- Isolates showed high MICs for meropenem and imipenem.
- Resistance was mediated by efflux systems (MexAB-OprM, TtgABC) and porin deficiency (OprD), without acquired carbapenemase genes.
Conclusions:
- First report of carbapenem-resistant Pseudomonas (P. aeruginosa, P. otitidis, P. putida) isolated from food.
- Resistance mechanisms primarily involve efflux pumps and porin alterations, not carbapenemases.
- Environmental spread and potential transmission of these resistant strains to clinical settings pose a public health risk.
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